Enzyme-responsive doxorubicin release from dendrimer nanoparticles for anticancer drug delivery

Abstract

Background

Since cancer cells are normally over-expressed cathepsin B, we synthesized dendrimer-methoxy poly(ethylene glycol) (MPEG)-doxorubicin (DOX) conjugates using a cathepsin B-cleavable peptide for anticancer drug targeting.

Methods

Gly-Phe-Leu-Gly peptide was conjugated with the carboxylic acid end groups of a dendrimer, which was then conjugated with MPEG amine and doxorubicin by aid of carbodiimide chemistry (abbreviated as DendGDP). Dendrimer-MPEG-DOX conjugates without Gly-Phe-Leu-Gly peptide linkage was also synthesized for comparison (DendDP). Nanoparticles were then prepared using a dialysis procedure.

Results

The synthesized DendGDP was confirmed with ¹H nuclear magnetic resonance spectroscopy. The DendDP and DendGDP nanoparticles had a small particle size of less than 200 nm and had a spherical morphology. DendGDP had cathepsin B-sensitive drug release properties while DendDP did not show cathepsin B sensitivity. Further, DendGDP had improved anticancer activity when compared with doxorubicin or DendDP in an in vivo CT26 tumor xenograft model, ie, the volume of the CT26 tumor xenograft was significantly inhibited when compared with xenografts treated with doxorubicin or DendDP nanoparticles. The DendGDP nanoparticles were found to be relatively concentrated in the tumor tissue and revealed stronger fluorescence intensity than at other body sites while doxorubicin and DendDP nanoparticles showed strong fluorescence intensity in the various organs, indicating that DendGDP has cathepsin B sensitivity.

Conclusion

DendGDP is sensitive to cathepsin B in tumor cells and can be used as a cathepsin B-responsive drug targeting strategy. We suggest that DendGDP is a promising vehicle for cancer cell targeting.

Keywords:

• cathepsin B
• CT26 cell
• enzyme-sensitive dendrimer
• tumor targeting
• tetra peptide

Supplementary materials

Figure S1 ¹H nuclear magnetic resonance spectra for the dendrimer molecule.

Note: Peaks of a and b was indicated methylene protons of dendrimer core.

Figure S2 ¹H nuclear magnetic resonance spectra for the Gly-Phe-Leu-Gly peptide.

Figure S3 ¹H nuclear magnetic resonance spectra for dendrimer-GFLG conjugate.

Note: Peaks of a and b was indicated methylene protons of dendrimer core.

Abbreviations: GFLG, Gly-Phe-Leu-Gly; EDAC, N-(3-dimethylaminopropyl)-N-ethylcarbodiimide hydrochloride; NHS, N-hydroxysuccinimide.

Figure S4 ¹H nuclear magnetic resonance spectra for the dendrimer-GFLG-mPEG conjugate.

Note: Peaks of a and b was indicated methylene protons of dendrimer core.

Abbreviations: GFLG, Gly-Phe-Leu-Gly; EDAC, N-(3-dimethylaminopropyl)-N-ethylcarbodiimide hydrochloride; NHS, N-hydroxysuccinimide; PEG, poly(ethylene glycol); MPEG, methoxy poly(ethylene glycol).

Figure S5 Synthesis scheme for DendDP conjugate.

Abbreviations: DendDP, dendrimer-MPEG-DOX conjugate; EDAC, N-(3-dimethylaminopropyl)-N-ethylcarbodiimide hydrochloride; DOX, doxorubicin; NHS, N-hydroxysuccinimide; MPEG, methoxy poly(ethylene glycol); TEA, triethylamine.

Figure S6 ¹H nuclear magnetic resonance spectra for DendGDP nanoparticles in double-distilled water.

Abbreviations: DendGDP, dendrimer-MPEG-DOX conjugate with GFLG peptide linkage; DOX, doxorubicin; MPEG, methoxy poly(ethylene glycol); GFLG, Gly-Phe-Leu-Gly; ppm, part per million.

Acknowledgments

This study was supported by a grant (2015–25) from the Biomedical Research Institute, Pusan National University Hospital.

Disclosure

The authors report no conflicts of interest in this work.